A generic access network (GAN), also known as a unlicensed mobile access (UMA) network, is a telecommunications system allowing handover between local area networks and wide area networks on a dual mode mobile device. The handover is seamless and can be between a cellular network such as a global system for mobile communication (GSM) network and a broadband network or Internet Protocol (IP) access network such as a wireless local area network (WLAN).
One problem with current GAN systems occurs during a mobile to mobile call if one of the mobiles abnormally releases the call. When the abnormal call release occurs, the second mobile device will not know the call has been released and keep network resources open, wasting network resources and battery life on the second mobile device. Abnormal termination may be caused, for example, by the battery being removed from the first mobile device or by the first mobile device going out of network coverage. Other abnormal call termination scenarios are also relevant.
Under the abnormal call termination, the network will eventually realize the call has been terminated and terminate the call with the second mobile device. However the eventual realization takes time, resulting in network resources and mobile device battery life being wasted.